Disk drives are widely used in computers and data processing systems for storing information in digital form. These disk drives commonly use one or more rotating storage disks to store data in digital form. Each storage disk typically includes a data storage surface on each side of the storage disk. These storage surfaces are divided into a plurality of narrow, annular regions of different radii, commonly referred to as “tracks”. Typically, a head stack assembly having a positioner and an E-block including an actuator hub is used to position a data transducer of a transducer assembly proximate each storage surface of each storage disk. The data transducer transfers information to and from the storage disk when precisely positioned on the appropriate track (also known as a “target track”) of the storage surface. A conductor assembly, including one or more trace arrays, electrically connects each data transducer to a drive circuitry.
The need for increased storage capacity and compact construction of the disk drive has led to the use of disks having increased track density or decreased track pitch, i.e., more tracks per inch. As the tracks per inch increase, the ability to maintain the data transducer on the target track becomes more difficult. More specifically, as track density increases, it is necessary to reduce positioning error of the data transducer proportionally. With these systems, the accurate and stable positioning of the data transducer proximate the appropriate track is critical to the accurate transfer and/or retrieval of information from the rotating storage disks.
In addition, the desire to reduce data transfer times requires faster storage disk rotation. High-speed disk drives can include a disk assembly that rotates 7,200, 10,000, or 15,000 revolutions per minute, or higher. These rapidly rotating storage disks generate substantial air turbulence within the drive housing of the disk drive.
Prior art FIGS. 1A and 1B illustrate a portion of a prior art disk drive. More specifically, FIGS. 1A and 1B illustrate a conventional actuator arm 22P, a conductor assembly 32P including portions of two trace arrays 36P, and a transducer assembly 28P (shown only in FIG. 1A) that are secured to the actuator arm 22P. The trace arrays 36P are generally flexible structures that run from the data transducer 70P, along the actuator arm 22P (only a portion is shown in FIG. 1A), to the drive circuitry (not shown in FIGS. 1A and 1B). Each trace array 36P typically includes a flexible, middle span 72BP that bows away from the actuator arm 22P.
One of the major drawbacks of conventional flexible trace arrays is that the turbulent airflow in the disk drive causes the trace arrays 36P to be intermittently driven into resonance. This motion of the conductor assembly 32P can pull the data transducer 70P off-track, creating errors known as track misregistration. Specifically, the non-repeatable component of track misregistration, known as “non-repeatable runout” (NRRO) is particularly impacted by the air turbulence created by the storage disks. In fact, the extent of the track misregistration increases exponentially with higher storage disk rotation rates.
FIG. 1C is a graphical representation of the level of NRRO measured at various disk drive frequencies for the prior art conductor assembly 32P depicted in FIGS. 1A and 1B. FIG. 1C includes measurements for a first data transducer and a second data transducer (neither data transducer is shown in FIG. 1A or 1B) connected to one actuator arm that is positioned between two storage disks (not shown in FIG. 1A or 1B). The cumulative extent of the NRRO is a statistical summation of the NRRO across a specified frequency range. The mathematical algorithm for performing this summation is well known to those practiced in the art. As used herein, NRRO is a distance that is expressed as a percentage of the width of a data track, which can be 0.5 microns, for example. In short, a higher percentage equates to a higher level of NRRO. In contrast, a comparatively lower percentage corresponds to a lower level of NRRO, resulting in a decrease in track misregistration. The measured level of NRRO for the first data transducer was 8.98%. The measured level of NRRO for the second data transducer was 10.06%.
One attempt to solve the problem of air turbulence causing track misregistration includes providing “air dams” to divert airflow away from data transducers and other components of the disk drive. Unfortunately, this approach has not been entirely satisfactory. For example, air dams are typically only utilized in more costly disk drives because they can add considerable expense to the manufacturing process. Additionally, air dams can be cumbersome to incorporate into the manufacturing process and they can impose restrictions on the overall design of the disk drive.
In light of the above, the need exists to provide a disk drive that accurately positions the data transducers relative to the storage disks. Another need exists to provide a reliable, simple, and efficient method to effectively reduce the sensitivity of the conductor assembly to the turbulent airflow caused by the rotation of the storage disks. Still another need exists to provide a means of decreasing the amount of airflow-induced excitation or resonance of the conductor assembly. Yet another need exists to provide a way to reduce or eliminate the non-repeatable component of track misregistration caused by the turbulent airflow of the disk drive.